安卓学习笔记_Day_06

不念不忘少年蓝@ 2022-02-05 04:11 239阅读 0赞

# RecyclerView的使用： #

主活动的界面：

<?xml version="1.0" encoding="utf-8"?>
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        xmlns:tools="http://schemas.android.com/tools"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".MainActivity">
    
        <android.support.v7.widget.RecyclerView
            android:id="@+id/recycler"
            android:layout_marginLeft="8dp"
            android:layout_marginRight="8dp"
            android:layout_width="match_parent"
            android:layout_height="match_parent">
    
        </android.support.v7.widget.RecyclerView>
    
    </LinearLayout>

列表子项目的xml文件：

<?xml version="1.0" encoding="utf-8"?>
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:id="@+id/item_root"
        android:orientation="horizontal"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">
    
        <ImageView
            android:id="@+id/header"
            android:paddingLeft="10dp"
            android:layout_width="80dp"
            android:layout_height="80dp" />
        <LinearLayout
            android:orientation="vertical"
            android:layout_width="match_parent"
            android:layout_height="wrap_content">
    
            <TextView
                android:id="@+id/name"
                android:paddingLeft="10dp"
                android:textSize="20dp"
                android:textColor="#2D72EB"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content" />
             <TextView
            android:id="@+id/desc"
            android:textSize="12dp"
            android:textColor="#DDBC58"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" />
        </LinearLayout>
    </LinearLayout>

为列表子项目创建的属性类：

public class Person {
    
        public String name;
        public String decs;
        public int id;
    
        Person(String name,String decs,int id){
           this.decs = decs;
           this.id = id;
           this.name = name;
        }
    }

主活动：

public class MainActivity extends AppCompatActivity {
    
        private RecyclerView recyclerView;
        private List<Person> personList = new ArrayList<>();
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            recyclerView = findViewById(R.id.recycler);
    
            //设置RecyclerView保持固定大小，这样可以优化RecyclerView的性能
            recyclerView.setHasFixedSize(true);
            LinearLayoutManager linearLayoutManager = new LinearLayoutManager(this);
            //设置RecyclerView的滚动方向
            linearLayoutManager.setOrientation(LinearLayoutManager.VERTICAL);
            //为RecyclerView设置布局管理器
            recyclerView.setLayoutManager(linearLayoutManager);
            initData();
            RecyclerView.Adapter adapter = new RecyclerView.Adapter<PersonViewHolder>() {
                @NonNull
    
                //创建列表项组件的方法，使用该方法所创建的组件会被自动保存
                @Override
                public PersonViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {
                    View view = LayoutInflater.from(MainActivity.this).inflate(R.layout.item1,null);
    
                    return new PersonViewHolder(view,this);
                }
    
    
                //为列表项组件绑定数据的方法，每次组件重新显示出来时都会重新执行该方法
                @Override
                public void onBindViewHolder(@NonNull PersonViewHolder viewHolder, int i) {
    
                    viewHolder.nameTv.setText(personList.get(i).name);
                    viewHolder.descTv.setText(personList.get(i).decs);
                    viewHolder.headerTv.setImageResource(personList.get(i).id);
                }
    
                @Override
                public int getItemCount() {
                    return personList.size();
                }
            };
    
            recyclerView.setAdapter(adapter);
    
        }
    
        private void initData(){
            String[] names = new String[]{
                    "爬升 " ,"速度" ,"将我推向" ,"椅背","模糊的城市" ,"慢慢地" ,"飞出" ,"我的视线"};
            String[] decs = new String[]{
                    "远离地面" ,"快接近三万英尺的距离" ,"思念像黏着身体的引力"
                            ,"还拉着泪不停地往下滴","逃开了你" ,"我躲在三万英尺的云底","每一次穿过乱流的突袭" , "紧紧地靠在椅背上的我"
            };
    
            int [] imagesIds = new int[]{
                    R.drawable.w1,R.drawable.w2,R.drawable.w3,R.drawable.w4,
                    R.drawable.w5,R.drawable.w6,R.drawable.w7,R.drawable.w8};
            for (int j = 0;j<names.length;j++){
    
                for (int i = 0;i<names.length;i++){
                    this.personList.add(new Person(names[i],decs[i],imagesIds[i]));
                }
            }
    
    
        }
    
        class PersonViewHolder extends RecyclerView.ViewHolder{
    
            View rootView;
            TextView nameTv;
            TextView descTv;
            ImageView headerTv;
            private RecyclerView.Adapter adapter;
    
            public PersonViewHolder(@NonNull View itemView, final RecyclerView.Adapter adapter) {
                super(itemView);
                this.nameTv = itemView.findViewById(R.id.name);
                this.descTv = itemView.findViewById(R.id.desc);
                this.headerTv = itemView.findViewById(R.id.header);
                this.rootView = itemView.findViewById(R.id.item_root);
                this.adapter = adapter;
                
                //子项目的点击监听事件
                headerTv.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                        Toast.makeText(MainActivity.this," 666", Toast.LENGTH_SHORT).show();
                    }
                });
                rootView.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                        int i = (int) (Math.random() * (personList.size() + 1));
                        Person person = new Person(personList.get(i).name,personList.get(i).decs,personList.get(i).id);
                        adapter.notifyItemInserted(2);
                        personList.add(2,person);
                        adapter.notifyItemRangeChanged(2,adapter.getItemCount());
                    }
                });
                rootView.setOnLongClickListener(new View.OnLongClickListener() {
                    @Override
                    public boolean onLongClick(View v) {
                        int position = getAdapterPosition();
                       //通知RecyclerView执行动画
                        adapter.notifyItemRemoved(position);
                        //删除底层数据模型中的数据
                        MainActivity.this.personList.remove(position);
                        //通知RecyclerView执行实际的删除操作
                        adapter.notifyItemRangeRemoved(position,adapter.getItemCount());
                        return false;
    
                    }
                });
            }
        }
    }